Friction stir welding (FSW) is a relatively new welding technique and has been used mainly for aluminum alloys in the transportation industry, in applications such as automobiles, railway vehicles, ships, and rockets. Effective friction stir welding conditions are known to the art. In one instance, prototype end domes for cryogenic tanks were fabricated using friction stir welding and spin forming deformation (SFD) (under spin forming deformation conditions, which are also known to the art). Subsequent heat treatment under effective solution heat treatment conditions to a high strength temper resulted in weldment properties that were below specifications. The weldment had reduced strength, fracture toughness, and/or ductility due to undesirably large grains. Abnormal grains can be detrimental to such notch-sensitive mechanical properties. Accordingly, a need exists for new treatments to improve weldment properties in manufactured articles.